Mechanism for controlling and indicating temperature limits.



No. 676,3". Patented lune n, ram. E. H. GRIFFITHS & w. c. u. wnmmn. IECHANISI FOR CONTROLLING AND INDICATING TEMPERATURE LIMITS,

(Application M Dec 19, 1900.)

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UNITED STATES PATENT OFFICE.

ERNEST II. GRIFFITHS AND WILLIAM C. D. WVHETHAM, OF CAMBRIDGE,

' ENGLAND.

MECHANISM FOR CONTROLLING AND INDICATING TEMPERATURE LIMITS.

SPECIFICATION forming part of Letters Patent N 0. 676,31 1, dated June 1 1, 1901. Application filed December 19, 1900. Serial No. 40,438- (No model.)

and useful Mechanism for Controlling and Indicating Temperature Limits, (for which we have made application for Letters Patent in Great Britain, dated March 27, 1900, No.

5,743,) of which the following is a specificat1on.

This invention relates to mechanism for controlling and indicating temperature limits, and has for its object to construct an apparatus which upon a temperature limit be- 7 ing reached will complete an electric circuit and cause an alarm to be sounded or some other function to be performed.

According to this invention acertain quantity of some fusible metal, alloy, or other conducting substance is so disposed within a suitable receptacle in relation to a contactpiece that upon the temperature limit being reached and the alloy fusedthe force of gravity or the action of a spring will cause contact to be made between the allow and the contact-piece, thereby completing an electric circnit. In our eonstruction the receptacle is made in the form of a metallic tube suspend-' ed in some suitable manner, with the lower end closed. The lower end of the tube-is bent, inclined, or otherwise shaped so as to form at one side of the tube, near its end a recess, pocket, or the like, within which the alloy will be retained'when in its solid state and the apparatus is set. I Opposite the reoess containing the alloy a contact-piece is so disposed that upon the temperature limit being reached, and the allow consequentlyfused or melted, it will run down to the extreme end of the tube and make contact with this contact-piece, thereby completing the electric circuit. This device may conveniently be made by cutting the end of a piece of tube and closing it in such a way that the bottom of the tube forms some angle other than a right angle with the axis of the tube. The upper open endof the tube is closed by an insulating-plug, through which passes a contact-wire of such length that the extreme end will lie in or adjacent to the extreme end of the tube, the alloy being retained in the obtuse angleof the end of the tube. The tube is suspended in such a manner that after the alloy has been fused and the contact made the device may be reset by raising the end of the tube while the alloy is in a fused or melted state, so that the contact will be broken, and retaining the tube in the raised position until the alloy has solidified. It is found advisable to provide the fusible Inetalor alloy with a coating of paraffin, wax, Vaseline, oil, or the like, which by lying on the top of the alloy prevents oxidation of the latter. In the accompanying drawings, Figure 1 is an elevation, partly in section, of a tempera cure-indicator in the form of a fire-alarmcom structed according to this invention. Fig. 2 is an end elevation of Fig. 1.

Like letters indicate like parts throughout the drawings.

A metal tube A, conveniently somewhat flattened, is cut at one end at an angle and closed by a plate A, an insulating-plug B beinginserted in the other end. The tube A is provided with a lug A by which it is pivot ally attached to a bracket, shown in the drawings in the form of tripod. The tube A is thus free to depend vertically clear ofany obstacle. The bracket is mount-ed conveniently on a base D.

Passing through the insulating-plug B and running almost to the bottom of the tube A is a wire E, which is covered by some insulating material E, but which has its point E uncovered. The upper end of the wire E is attached to a terminal F,-carried on the base D. To the metal tube A or the lug A is attached a conducting-Wire E whose other end is connected to a terminal F, also on the base D. Situated in the obtuse angle A of the tube A is some alloy G which will fuse when the desired temperature limit is reached or exceeded and run down the inclined plate A at the bottom of the'tube into the acute angle A When in this position, the alloy G will surround the point of the wire E and thus close the gap between the tube A and the wire E. Wires H connect the terminals to an electric-bell circuit or other form of alarm,-which will be operated directly the gap is closed by the fusion of the alloy.

To reset the apparatus, the tubeAis turned about its pivot and brought into the position shown in dotted lines in Fig. 1. Heat is applied so as to fuse the'alloy G which then runs back into its former position in the obtuse angle A When the alloy has solidified, the tube is turned'or allowed to fall back into the vertical position, so as to be again ready for use. Stops J J limit. the movement of the tube A about its pivot and prevent it as set forth.

from being raised too far when resetting.

What we claimas our invention, and desire, to secure by Letters Patent, is'

1. In an apparatus for controlling or. indi- I eating temperature limits, the combination 5 of a receptacle hung for angular movement,

an electrical circuit normally having in it a" gap anda fusibleconductingsubstance con stituting a gravity-switch in thereceptacle, substantially as set forth. Y

,2. In an apparatus for controlling orindi cating temperature limits the combination I of a tubular receptacle with an inclinedbot. tom, an electrical circuitincluding the receptacle and normally having in it a gapand a fusible conducting substance constitutinga gravity-switch in lhereceptacle substantially 3. In an apparatus for controlling or in'di-j l eating temperature limits, the combination.

of a'pivoted receptacle, stops to limit the movement of the receptacle about its pivot, an electrical circuit including the receptacle I and-.normallyhaving in it'a gap and a fusible conducting substance constituting a gravityswitchin the receptaclesubstantiallyas set I forth.

the gap in the electrical 4. In an apparatus forcontrolling or indicating temperature limits the combination of a pivoted tubular receptacle having an inclined bottom, an electrical circuit including the receptacle and normally having in it a gap and a fusible conducting substance constituting a gravity-switch in the receptacle substantially as set forth.

5. In an apparatus for controlling or indicating temperature limits, the combination of a pivoted tubular receptacle having an inclined bottom, stops for limiting the movement of the'receptacle about its pivot, an electrical circuit including the receptacleand normally having in it a gap and a fusible con ducting substance constituting a gravityswitch in forth.

the receptaclesubstantially as set v 6. In an apparatus for controllingor ind-icating temperature limits the combination of a pivoted receptacle with an inclined bottom, a wire passing through an insulatingp'lug carried in the open end of the. tubular receptacle the end of the wire lying in the acute angle at the bottom of the receptacle, an electrical circuit including the receptacle and thewir'e and normally having in it'a gap between the .end of the wire and the bottom of the receptacle and a [fusible conducting substance normally situated in the obtuse angle at the bottom of the receptacle and con: stituting a gravity-switch operating to close as set forth. 1 l I I 1 In testimonywhereof we have signed our names to this specification in the presence of two subscribing witnesses; j v E. H. GRIFFITHS.

V is O. D.'WHETI IAM. Witnesses: I I I I PERCY M. ll/IARSHALL,

CHAR S E. LAWRENCE.

circuit substantially 

